Compound step

Iteration

a step to iterate over 2 sequences, like a p:for-each but with 2 iteration sources that are iterated in parallel (1st doc of each, 2nd doc of each, etc). (can be covered by p:pack / p:for-each / p:unwrap)

input

a step that accepts (and waits) for external input

resource manager step

provide step for overriding URI - assumes the existence of some kind of resource manager